Chemistyr Flashcards
What is the periodic table?
A list of all the known elements
What two main categories are there in the periodic table?
Metals and non metals
Group and period meaning
Group is down and period is across
Metal characteristics
high melting points.
good conductors of electricity.
good conductors of heat.
high density.
malleable.
ductile.
lustrous and shiny.
solid at room temperature except for mercury (liquid)
What happens when metals react with oxygen?
Metal + oxygen —-> metal oxide
What happens when metal reacts with water? Especially G1
Metal + Water Metal hydroxide + hydrogen
What are some group 1 metals
Lithium, sodium, and potassium
What are the group 1 metals also known as
Alkali metals
Properties of G1
are soft (they can be cut with a knife)
have relatively low
melting points
The alkali metals also have low
densities
. They are low enough for the first three (lithium, sodium and potassium) to float on water.
has a pH greater than 7 when dissolved in water
They must be stored under oil to keep air and water away from them. When they react with water, Group 1 elements form metal hydroxides which are alkaline. (with a pH above 7). This is why they are called alkali metals.
Reactivity of L,S and P when contacted with water
Lithium, Li Fizzes steadily, slowly becomes smaller until it disappears
Sodium, Na Melts to form a ball, fizzes rapidly, quickly becomes smaller until it disappears
Potassium, K Quickly melts to form a ball, burns violently with sparks and a lilac flame, disappears rapidly, often with a small explosion
Reactivity trend in G1 metal as you descend
As you go down the group the reactivity is greater. This is because they are metals and they loose an electron when they react. The further away the electrons are from the nucleus, the easier it is to loose one as the force of attraction decreases.
How do you test for hydrogen with a lit splint?
holding a burning splint near to the top of the test tube for the squeaky pop test.
What are group 2 metals called
Alkaline earth metals
What happens when strontium, calcium and magnesium are added to water
These all react with cold water with increasing vigour to give the metal hydroxide and hydrogen. Strontium and barium have reactivities similar to lithium in Group 1 of the Periodic Table.
Calcium, for example, reacts fairly vigorously with cold water in an exothermic reaction. Bubbles of hydrogen gas are given off, and a white precipitate (of calcium hydroxide) is formed, together with an alkaline solution (also of calcium hydroxide - calcium hydroxide is slightly soluble).
Very clean magnesium ribbon has a very slight reaction with cold water. After several minutes, some bubbles of hydrogen form on its surface, and the coil of magnesium ribbon usually floats to the surface. However, the reaction soon stops because the magnesium hydroxide formed is almost insoluble in water and forms a barrier on the magnesium preventing further reaction.
Trend of reactivity in AEM
Same as G1 metals
Describe the relative reactivity of the Alkaline Earth metals compared to the Alkali metals
Less reactive
What are the group 7 metals also known as
Halogens
Chlorine
Yellow - green gas
Use : disinfect water
Fluorine
Yellow - green gas
Use : creating nuclear material for nuclear power plants
Bromine
Red / brown liquid
Use : agricultural chemicals
Iodine
Grey solid
Use : printing inks
What is a diatomic molecule
Molecules composed of one two atoms
Chlorine reaction to iron wool
Burning, sparks, flame producing an orange gas. Iron goes yellow. Orange gas = iron chloride
Bromine reaction to iron wool
Bit of flame (less then chlorine), glows, goes brick red. Orange gas
Iodine reaction to iron wool
Sublimation, purple gas, no sparks, gas produced
Word equation
Halogen + iron ——> iron halide
Reactivity trend
As they are nonmetals, they gain an electron. This means the reactivity decreases. This is because it is easier to gain an electron than to loose seven as they want to react the outer shell. It produces metal halide
Describe the structure of an atom
a central nucleus, composed of protons and neutrons, surrounded by electrons, orbiting in shells
Relative charge
Protons : +1
Neutrons : 0
Electron : -1
Relative mass
Protons : 1
Neutrons : 1
Electron : 1/2000
Atomic number
the number of a chemical element in the periodic system and on the periodic table that equals the number of protons in the nucleus of the atom.
Atoms have no mass
Mass number
the total number of protons and neutrons in an atom
Isotopes
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei
Relative atomic mass
Relative atomic mass is determined by the average atomic mass
((Isotope * abundance) + (isotope * abundance))/100
Describe the arrangement of electrons in shells for the first 20 elements
Outer shell no of electron = group no. Shells inside that are full
relationship between group number and period number with electron arrangement
Group no = outside shell electron
Period = shells
What is an atom?
a small particle that all things are made of.
What is an element?
an element is made up of only one type of atom.
What is a compound?
two or more different elements bonded together.
properties of a compound are different to the properties of the elements used to make them
Work out the name of a compound made up of a metal and non-metal elements.
Metal non - metal ide
What is a mixture?
two or more substances not chemically bonded together.
What is a molecule?
two or more non-metal atoms bonded together
A molecule can be an element or a compound
Draw particle pictures to describe the composition of elements and molecules.
See book
Practice balancing chemical equations
Mass changes
Mass conserved : it stays the same
Mass increase : start with a gas
Mass decreases: end with a gas
What is a hydrocarbon?
molecule/compound which contains only the elements carbon and hydrogen chemically
bonded together.
Hydrocarbons have different numbers of carbons
What is the main source of hydrocarbons
Crude oil
What is crude oil
A mixture of different hydrocarbons and small amount of other substances
Hydrocarbons uses
fuels and lubricants as well as raw materials for the production of plastics, fibres, rubbers, solvents, explosives, and industrial chemicals
What is combustion?
A type of chemical reaction between hydrocarbons and oxygen
Conditions for combustion
There must be Fuel to burn. There must be Air to supply oxygen. There must be Heat (ignition temperature) to start and continue the combustion process.
Word equation for combustion
Hydrocarbons + oxygen - ——> carbon dioxide + water
Must happen in a plentiful supply of oxygen
Test for water
Adding water to Anhydrous copper ll sulfate
Positive turns blue
Test for carbon dioxide
Bubble gas through limewater
Positive test: cloudy lime water
